활성 표지 선발법을 이용한 애기장대 저온 저항성 돌연변이체 선발 및 특성 분석

Abstract

Low temperature is one of the most important environmental stress that lead to the various response of plants such as cold acclimation and vernalization. Also extremely low temperatures(freezing temperatures) limit the geographical distribution of plants and cause severer losses in crop plants. Thus, freezing tolerance in crop plants is an important trait for its commercial value. To find the possible genetic resource, a series of mutants were isolated with enhanced freezing tolerance in the absent of cold acclimation by screening for Arabidopsis activation tagging mutants. Arabidopsis activation tagging mutant showing resistance against freezing was screened from 80,000 T1 activation tagged line. One mutant, freezing-tolerant line 1-Dominant(ftl1-1D), showed dark green, dwarfism and late-flowering. To get inside into molecular function of Freezing-Tolerant Line(FTL1), the FTL1 gene was isolated by using plasmid DNA rescue. The rescued DNA sequence was perfectly matched to AT1G12610(DDF1) of Arabidopsis genomic DNA sequence. Dwarf and Delayed Flowering 1(DDF1), a gene previously reported that FTL1/DDF1 encodes AP2 transcription factor and is involved in the regulation of GA biosynthesis and stress tolerance. ftl1-1D/ddf1 mutant enhanced not only cold tolerance, but also heat and drought tolerance. However, these phenotype were restored by exogenous gibberellin(GA3). To examine the FTL1/DDF1 gene expression pattern under abiotic stresses, we monitored the time course of the accumulation of FTL1/DDF1 mRNA under abiotic stresses by real-time PCR in wild type. The level of FTL1/DDF1 mRNA in wild type showd that FTL1/DDF1 gene expression is induced by cold, heat, drought and salt stresses. Therefore, FTL1/DDF1 plays a role in regulating responses to several abiotic